Lubricating composition



lit. 2x21511598 Patented Sept. 24, 1940 UNITED STATES oss Reference LUBRIOATING C'OMPO SITION George M. Maverick, Elizabeth, N. J., assignor to StandardOil Development Company, a corporation of Delaware No Drawing. Application July 20, 1935,

' Serial No. 32,380

.7 Claims.

The present invention relates to lubricating compositions and to methods for producing the same, and more specifically to a lubricant capable of carrying heavy loads and of reducing friction. The nature of the composition and its ingredients will be fully understood from the following description.

Lubricants, especially the oils for modern motor vehicles, have within recent years been subjected to conditions of load, speed and the like never before encountered. It has been long realized that hydrocarbon oils are not naturally endowed with ideal properties for severe service. For example, they do not possess oiliness .or

lubricating properties to so high a degree as might be desired. They tend to deteriorate by oxidation and sludge formation and while there are now no satisfactory substitutes for them, it is highly desirable to improve the natural oils in respect to these properties. While hydrocarbon lubricants are adequate at the present time, it is very desirable to further increase loads and speeds and improved oils must be found to meet' this demand.

In the present invention mineral oils are greatly improved, particularly in respect to carbonforming tendencies, load carrying capacity or oiliness and tendencies toward oxidation by the addition of relatively small amounts of certain materials. The. materials which are added are included within the broad class of phthalic acid compounds and among these esters are also included those of isophthalic and terephthalic acids as well as the simple derivatives such as the alkylation products.

These various. acids are preferably esterified with various alcohols and among these the simple aliphatic alcohols may be' used such as methyl, ethyl, the propyl, the butyl and the amyl alcohols and these are for many purposes the most satisfactory, although the higher alcoholic esters are also quite useful such as the phthalates of cetyl, lauryl, octadecyl, oleyl and the like. Esters of aromatic alcohols or phenols may also be included such as phenyl, cresyl or benzyl phthalates and especially the alkylated phenyl phthalates. The mono alkyl esters are satisfactory but for most purposes the dialkyl esters are preferable such as diethyl, dibutyl or dicresyl phthalates, and among the alcohols the monohydric groups are to be preferred, although polyhydric alcoholic esters such as those of glycol and glycerol may be included.

Other phthalic esters which may be employed are butyl benzyl phthalate, glycol ether phtha- (Cl. 252-57) lates, dibutoxy ethyl phthalate, di (beta phenoxyethyl) phthalate, di (betabutoxy ethyl) glycol di-phthalate, hydrogenated phthalates, and the like.

The materials mentioned above 'are added to the oils in amounts ranging from up to 10%, although for most purposes about 2% is quite satisfactory. They are quite effective for the purposes outlined above in this concentration although for. some special uses relatively large amounts may be desirable.

These agents may be added to the lubricating oils for use in automobile engines or in steam cylinder oils, various industrial lubricants and the like, or they may be included as ingredients in grease compositions such as are adapted for use where a higher degree of oiliness is required than is ordinarily offered by the common greases now available.

The esters first described, as stated before, may

be added to any types of lubricating, oils, for example those derived from paraflinic, napthenic or asphalt base crudes such as may be refined by the ordinary methods of refining now commonly in use and they also may be used as addition agents to oils which have been refined by special processes such as solvent extraction, hydrogenation or the like. The base stocks should be well refined and of a good quality and while the particular compositions made up with mineral oils alone are of especial value, particularly for motor lubrication, it should be understood that other ingredients such as soaps maybe added even to such large proportions as to solidify the oil.

The addition of as much as 10% of the phthalic esters reduces the viscosity of the oilblend and moreover changes an S. A. E. 30 grade to 20 but such oils have considerably greater oiliness than the unblended oils of greater viscosity and there is no danger in using a 20 blend where a 30 unblended oil was previously used.

An oil having viscosity of 550 and 64.2 seconds Saybolt respectively at 100 and 210 F. when blended with 10% dibutyl phthalate showed viscosities of 374 and 56 seconds at 100 and 210? F.-

respectively.

' The addition agents may be psed in straight mineral oils or they may be added to blended oils which contain other ingredients, for example,

pour inhibitors, anti-oxidants, dyes, thickeners 50 I and the-like. As examples of the new compositions, the following may be considered:

ExampleI The lubricating oil selected for the following SEARCH ROOM 2,215,590; q

comrosmcms.

tests is an S. A. E. 20 base stock of good quality. One sample of this oil is used as a blank and to other samples the various phthalic acid esters have been added. The table below shows some of the physical properties of these oils:

Sample No. min

1 Hydrocarbon lubricating oil. 1620 2 Same +l% dimcthyl phthalate. 09 8. 4 1380 3 Same +l% dicthyl phthalate. 06 6. 7 1020 03 5. 0 1620 Example II The oxidation rates of the various samples listed in Example I were determined by passing oxygen at a definite and uniform rate through a cyclic path which includes a container in which inch pounds.

perature of 200 C- The oxygen bubbles through, oil and at intervals of 15 minutes the amount of oxygen absorbed is determined by difference from the volume remaining. The table below shows the oxidation rates of the various samples in. Example I:

Oxidation rate at 200 0.,

Sample cc. 03/10 cc. Sample/15 minutes m 1 Hydrocarbon oil (i2 93 56 2 Same+l% dimethyl phthalatc. 28 59 59 34 3 Same+l% diethyl phtha-late 37 53 40 39 40 49 43 42 4 Same-H7 dibutyl phthalate The rate of oxidation is considerably reduced by the addition of the phthalic esters.

Example III In order to show the oiliness properties runs were made with the samples shown in Example I, on the Mougey machine according to the meth- 0d of Mougey and Almen, National Petroleum News, November 11, 1933, page 47. The pin in these particular tests was steel and the bushings aluminum.

Mougey test Samples Weights Final carried friction 1 Hydrocarbon oil L l7 Sheared 2 Same+1% dimcthyl phthalate. 25 29 3 Same+l% diethyl phthalato p 25 23 4 Same+1% dibutyl phthalate 25 23 The samples conta' ing the esters carried the full 25 weights, the highest load called for by the. test, and at the low frictional values of 23 to 29 Example I V- In practical operation in automotive engines 'the oils containing phtha c esters showed valuable properties. Comparative tests were made on a Universal -engine, one run on an unblended S. A. E. 30 oil and the other with the same oil truss iiBTBlBflCB part of a prior application December 20, 1933;

' was 7.7 grams or 52 grams/pound of oil.

Similar tests in a Chevrolet engine gave 14.9 grams of carbon (total) for the 10% dibutyl phthalate blend or 4.0 grams/pound ofoil as against 18.8 grams total or 5.9 grams/pound of oil for unblended hydrocarbon lubricant used.

Example V I Tetrahydro phthalic acid is produced by reac-v tion of maleic anhydride and butadiene under known conditions. The product was then esterifled with isopropyl alcohol. To an S. A. E. 20 grade lubricating oil 20% -of this ester is added. Sligh tests and oxidation rate tests were then the base oil and the blend. The Sligh tests were made in the usual manner; and the according to the method of The results are as follows:

oxidation rate test Example 11 above.

Oxidation rate,

cc. 01/10 cc. Samplo Shgh Sample/l5 min.@

/ Unblended oil 38.0 629356 Oil+.2% tetrahydro isopropyl phthalate 33. 8 -8147 The Sligh value is decreased and the initial oxidation raised although it soon becomes lower.

- Example VI The same oils described in Example V were tested for frictional characteristics in the Almen machine in steel to steel bearings with the following result:

E. 20+tetrahydro isopropyl pbthalato 7 The blended sample carried more than twice SEARCH ii the weight of the unblended oilv before breakdown.

The present is a continuation in Ser. No. 703,213 filed application This invention is not to be limited by any theory of the improvement which is wrought by the particular composition nor by any specific esters or oils but only by the following claims in which it is desired to claim all novelty inherent in the invention.

I claim:

1. A lubricating composition containing a major proportion of a viscous hydrocarbon lubrieating oil and a minor proportion of a phthalic ester.

2. A lubricant comprising a viscous hydrocar-. bon lubricating oil and a minor quantity up to about 10% of an ester of phthalicacid.

3. Lubricant according to claim 2 in which the ester is a monohydric alcoholic ester of phthalic acid. Y

4. Composition according to claim 2 in which Q 0 iii .the ester is a dialkyl ester derived from mono- 6. Composition according to claim 2 in which hydric alcohols and phthalic acid. the ester is dibutyl phthalate.

5. Composition according to claim 2 in which '7. Composition according to claim 2 in which /2 to 10% of a dialkyl ester of phthalic acid is the dialkyl ester is used, the ester being prepared 5 used, the alkyl groups being selected from the from a higher alcohol and phthalic acid. 5

lower alkyl radicals. GEORGE M. MAVERICK. 

